What is evidence in an experiment?
evidence; information gathered from observations/experiment control group In an experiment, the group that is not exposed to the treatment; contrasts with the experimental group and serves as a comparison for evaluating the effect of the treatment. prediction
What are the characteristics of an experiment?
The measurable effect, outcome, or response in which the research is interested. trial each repetition or observation of an experiment Inference A conclusion reached on the basis of evidence and reasoning experiment A research method in which an investigator manipulates one or more factors to observe the effect on some behavior or mental process
What is the difference between control group and experimental group?
control group In an experiment, the group that is not exposed to the treatment; contrasts with the experimental group and serves as a comparison for evaluating the effect of the treatment. prediction
What is a plot in an experiment?
The individual things that you wish to test in your experiment are called "treatments" and the physical areas to which the treatments are applied are called "plots." Then you need to decide how the treatments should be physically arranged in the field. Technically, this is what is called the "experimental design."
What provides a basis of comparison in an experiment?
control group, the standard to which comparisons are made in an experiment.
What is a point of comparison in an experiment?
observation. A standard for comparison that helps to ensure that the experiment result is caused by the condition of being tested is the. control. A factor in an experiment that changes from one manipulation of the independent variable is the. dependent variable.
What is a placebo and what purpose does it serve in an experiment quizlet?
a. The placebo is a medication that looks, smells, and tastes like Lipitor. The placebo control group serves as a baseline against which to compare the results from the group receiving Lipitor. The placebo is also used because people tend to behave differently when they are in a study.
How is a placebo group used in an experiment quizlet?
How is a placebo group used in an experiment? - one group of subjects receives a treatment and the other group receives a fake treatment.
What is used for comparison?
Adjectives and adverbs can be used to make comparisons. The comparative form is used to compare two people, ideas, or things. The superlative form with the word "the" is used to compare three or more. Comparatives and superlatives are often used in writing to hedge or boost language.
How do you compare two experiments?
To compare them accurately, answer the following questions as you read:How is each experiment set up? Make sure you understand the method for each experiment. ... What does the data show? Pay close attention to the results of each experiment. ... How do the experiments differ?
When applying the same treatment to more than one experimental unit What is the process called?
Replication occurs when each treatment is applied to more than one experimental unit. Using more than one experimental unit for each treatment ensures the effect of a treatment is not due to some characteristic of a single experimental unit.
What is the purpose of the random assignment of treatments to subjects in an experiment quizlet?
The purpose of random assignment is to allow the experimenter to prevent the participants from knowing which condition they were assigned to.
What is an experiment in which the experimental unit or subject does not know which treatment he or she is receiving called?
CardsTerm ExperimentDefinition A controlled study conducted to determine the effect of varying one or more explanatory variables or factors has on a response variableTerm Single blindDefinition An experiment in which the experimental unit does not know which treatment he/she is receiving36 more rows•Nov 2, 2013
How is a placebo group used in an experiment?
In order to make sure a new drug or vaccine is effective, studies often use a placebo or control group. Placebos are “sugar pills” or “dummy drugs” with no active ingredients and are made to look like the real medicine. A control is a standard treatment (that may be currently used) for the illness.
Why are placebos used in some research studies quizlet?
The major advantage of using a placebo when evaluating a new drug is that it weakens or eliminates the effect that expectations can have on the outcome. If researchers expect a certain result, they may unknowingly give clues to participants about how they should behave. This can affect the results of the study.
What is the purpose of the placebo group quizlet?
The purpose of a placebo is to prevent participants from knowing whether they belong to the treatment group or the control group.
What is the goal of an experiment?
The goal of the experiment will dictate what to include in the experiment to help you answer your question. The individual things that you wish to test in your experiment are called "treatments" and the physical areas to which the treatments are applied are called "plots.".
How to do a two factor experiment?
Most simple on-farm experiments are single-factor experiments (in a Completely Randomized or Randomized Complete Block design) and compare things such as crop varieties or herbicides, but it is sometimes useful to test two or more factors at once. For example, a two-factor experiment would allow you to compare the yields five corn hybrids at three planting dates. This accomplishes three things at once: 1 It allows you to compare the corn hybrids with each other. 2 It allows you to evaluate the effect of planting date. 3 It allows you to determine if varying the planting date changes the relative performance of the hybrids (e.g. one hybrid may only perform well if planted early).
Why is replication important in an experiment?
Replication is necessary because all test plots are not identical, and that leads to variation in the data you collect; you will not get exactly the same results from two plots that received the same treatment. You can take steps to minimize the effect of variation if it has an identifiable cause, but there will always be some variation among plots that cannot be controlled. In statistical terms, uncontrolled variation is called experimental error. The purpose of replication is to allow you to make a more accurate estimate of how each treatment performed even though there is uncontrolled variation in the experiment. This can best be shown in an example.
Why is it important to write down the test objectives?
Writing down the test objectives is helpful because this forces you to define them precisely. A test may have more than one objective, although multiple objectives should be closely related.
Can a test have more than one objective?
A test may have more than one objective, although multiple objectives should be closely related. The selection of treatments is usually logical if you can define the purpose of the study; all treatments necessary to address the test's objective should be included.
Can you compare the options by conducting your own small experiments?
Often the information needed to make the best decision is available to you, but when it is not available you can frequently compare the options by conducting your own small experiments. Your experiments can be just as valid as any university study if you follow a few important principles of experimental design.
Can you have two fungicides in an experiment?
For example, if you currently can choose either of two fungicides to control a leafspot problem, you may wish to include them both as controls in your experiment when you test new products.
Selecting Treatments
Replication
- In an experiment, replication means that individual treatments (such as each of the five pesticides being tested in an experiment) have been applied to more than one plot. Replication is necessary because all test plots are not identical,and that leads to variation in the data you collect; you will not get exactly the same results from two plots th...
Randomization
- Randomization in an experiment means that the treatments are assigned to plots with no discernable pattern to the assignments. The reason randomization is important is that the positioning of treatments within the block may affect their performance. One example of this is an experiment testing five corn hybrids (labeled 1 through 5) in which you plant the hybrids in the s…
Plot Size
- A plot, the area to which an individual treatment is applied, can be any size, including a single plant growing in a pot or 5 acres or more of a field. Before you can apply treatments to your test area, you must decide how large your plots should be. Although there is a lot of subjectivity in selecting plot size, there are some important considerations including the equipment to be used …
Experimental Designs
- Completely Randomized Design
The completely randomized design is the simplest experimental design. In this design, treatments are replicated but not blocked, which means that the treatments are assigned to plots in a completely random manner (as in the left side of figure 2). This design is appropriate if the entir… - Randomized Complete Block Design
The randomized complete block design is the most commonly used design in agricultural field research. In this design, treatments are both replicated and blocked, which means that plots are arranged into blocks and then treatments are assigned to plots within a block in a random mann…
Data Collection
- You can collect an almost infinite amount of data in any experiment, but not all of it will be useful. Proper planning will ensure that you collect the right data to address your test's objective. The "right" data to collect can usually be determined by examining the stated purposes of the experiment. For example, if the objective of a peanut leafspot fungicide trial is "to evaluate the a…
Collecting Unbiased Data
- It is critically important to collect unbiased data.The only way to ensure this is to collect data without knowing what the treatment was in that plot. That would be difficult to do if the treatment were written on a stake in front of each plot. It is beneficial to use some type of code on the plot stakes so that you have to decode the stake number to determine what the treatment was. You …
Statistical Calculations
- After collecting data from a properly designed experiment, you will usually need to analyze the data with appropriate statistical calculations. Statistical analysis may not be necessary if treatment differences are very large and consistent; treatment means may then be sufficient. Statistical analysis is beyond the scope of this publication. Proper statistical analysis can be do…
Summary
- The following checklist can be used in designing an experiment. These items may be addressed in any order. 1. Determine the objective of the test. 2. Select treatments to address the objective. Consider including positive and negative controls. 3. Determine what data should be collected, and when it should be collected, to address the objective. 4. Select the number of replications t…